Enzymatic degradation of poly([R,S] β-hydroxybutyrate)

The synthetic analogue of a bacterially produced polyester, poly(-hydroxybutyrate) (PHB) was synthesized from racemic -butyrolactone using anin situ trimethyl aluminum-water catalyst. The polymer was fractionated into samples differing in molecular weight and isotactic diad content. The latter was closely related to degree of crystallinity. The biodegradation of these fractions were examined by monitoring mass loss over time in the presence of anAlcaligenes faecalis T1 extracellular bacterial poly(-hydroxybutyrate) depolymerase. The fraction with high isotactic diad tacticity content showed little or no degradation over a 50 hour incubation period, whereas the fraction of intermediate isotactic diad content degraded in a continuous steady fashion at a rate that was less than that for bacterial PHB. The low isotactic diad fraction underwent a rapid initial degradation, followed by no further mass loss. The presence of stereoblocks in the polymer structure of the various fractions was an influence on the degree of susceptibility towards degradation and is related to sample crystallinity.     

沈阳市降雪中PFOS和PFOA污染现状调查

通过调查降雪中PFOS和PFOA的浓度,阐明了沈阳市大气中PFOS和PFOA的污染状况和污染规律.2006-02-06采集沈阳市区和郊区共计36个采样点的降雪样品,2006-02-25在其中5个采样点再次采集降雪样品.固相萃取融雪水中的PFOS和PFOA,利用LC-MS-SIM法测定样品中PFOS和PFOA浓度.全部样品中均检出PFOS和PFOA.2006-02-06降雪中PFOS和PFOA的浓度几何平均值分别为2.0 ng·L^-1（范围：0.4～46.2 ng·L^-1）和3.6 ng·L^-1（范围：1.6～22.4 ng·L^-1）,95%置信区间分别为1.5～2.8 ng·L^-1和3.1～4.2 ng·L^-1.PFOS和PFOA的最高浓度同时出现在郊区采样点朱尔屯,市中心区2种物质的浓度呈显著正相关.2006-02-25的5个采样点降雪中PFOS和PFOA的浓度几何平均值均为2.2 ng·L^-1.2次降雪中PFOS浓度差异不显著,2006-02-25降雪中PFOA浓度高于2006-02-06.结果表明,沈阳市区和郊区降雪中广泛存在PFOS和PFOA污染,局部区域可能存在共同的PFOS和PFOA污染来源;沈阳地区有较稳定的PFOS来源持续向大气中输送该类物质;PFOS和PFOA的环境行为可能不同.     

Initial design process of the sustainability science ontology for knowledge-sharing to support co-deliberation

Implementation of the sustainability science (SS) approach is often difficult because of poor communication between experts from different academic fields. We focused on ontology engineering as a method of knowledge structuring that supports the co-deliberation process. However, SS is too broad for a few experts to construct an ontology because SS targets and covers almost all existing research fields from the viewpoint of problem-solving. The N-iteration process is required for completing an SS ontology. In the present paper, we discuss the initial design process for constructing an ontology on SS from the aspect of a knowledge-sharing tool to support co-deliberation. First, we identified the SS ontology by referring to the existing literature. Second, we traced the structuring process of the SS ontology, which is independent of the existing research domain. Third, we compared the SS ontology with existing ontologies or concept structures on SS. Fourth, we assessed the SS ontology produced in the initial process in terms of relevance and coverage and addressed areas for improvement in order to facilitate co-deliberation among researchers from different domains. As a result of developing the SS ontology and applying it to the mapping tool that we developed based on the ontology, we found the following three points: the SS ontology enables us to define concepts relevant to SS without overlapping by distinguishing part-of and attribute-of relationships at the upper level of the ontology; the SS-based mapping tool successfully represents the potential countermeasures required by the targeted problem for all scientific fields except experimental engineering; however, the SS ontology requires further improvement in order to represent the conceptual linkage arising from compound and secondary problems and the fulfillment of classes at the lower hierarchy of Shortage problem, and requires slots for the entire hierarchy. In addition, based on the discussion of the areas for improvement, we found that missing slots and classes should be added in the process in which we use or improve tools corresponding to a variety of requirements for supporting co-deliberation. In this way, we are able to propose an incremental process for constructing the SS ontology from the aspect of a knowledge-sharing tool to support co-deliberation.     

Perfluorosulfonates and perfluorocarboxylates in snow and rain in Dalian,China

Samples of precipitation events (snow and rain) in Dalian, a typical coastal town in China, were analyzed for perfluorosulfonates (PFSAs) and perfluorocarboxylates (PFCAs) to investigate atmospheric contamination by these compounds. In the snow event on December 16, 2006, samples were collected from 21 different sites and in another 6 precipitation events, samples were collected from a single location. Four PFSAs (C4, C6, C8, C10) and seven PFCAs (C6–12) were analyzed. Among the homologues, perfluorooctane sulfonate (PFOS) concentrations were the highest with a geometric mean (GM) of 145 ng/L (n = 21) during the snow event on December 16, 2006, followed by perfluorooctanoate (PFOA) with a GM of 24.7 ng/L (n = 21). Concentrations of perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS) and perfluoroheptanoate (PFHpA) were more than two orders of magnitude lower than that of PFOS. Other PFSAs and PFCAs were found to be below the limit of detection in all the samples. In other 6 precipitation events, PFSAs and PFCAs were detected approximately in the same order of magnitude in both snow and rain. The results indicate that wet deposition may be a potential transport mechanism of perfluorinated chemicals in the environment.     

Purification and characterization of extracellular poly(3-hydroxybutyrate) depolymerases

Five extracellular PHB depolymerases of bacteria isolated from various sources were purified to electrophoretic homogeneity and compared with known extracellular PHB depolymerase fromAlcaligenes faecalis T1. The molecular mass of these enzymes were all around 40–50 kDa. Nonionic detergent, diisopropylfluorophosphate and dithiothreitol inhibited the PHB depolymerase activity of all these enzymes. Trypsin abolished PHB depolymerase activity, but not theD-3-hydroxybutyric acid dimer hydrolase activity of all the enzymes. These results showed that the basic properties of these PHB depolymerases resemble those of theA. faecalis T1 enzyme. Analysis ofN-terminal amino acid sequence of the purified enzymes revealed that these enzymes includingA. faecalis T1 enzyme fall into three groups.     

Respiratory tract retention of inhaled air pollutants: Report 1 : Mercury absorption by inhaling through the nose and expiring through the mouth at various concentrations

To study atmospheric mercury absorption in human respiratory passage-ways, mercury in expired air was measured in three different states of breathing: steady breathing, deep breathing and breath held after inspiration.In this study, air containing mercury was inhaled through the nose and expired through the mouth. The concentration of mercury in the exhaled air was determined by the technique of gold-amalgam trapping, heat vaporization, and flameless atomic absorption measurement.The subjects were 13 male adults, aged 25–62 years, and 38 cases were observed. Four different concentrations of mercury, 1–3, 4–6, 10–11, and 20–30 μg/m³ were used, and absorption for each was determined. When the concentration was 1–3 μg/m₃, the absorption was 74–92%, the average being 82.5%. At concentrations of 4–6, 10–11, and 20–30 μg/m₃, the absorption was 76.6–100%, 75.5–99.2%, and 79.9–95.9% respectively, and the average was 88.8%, 85.2%, and 87.7% respectively.A slightly higher rate of mercury absorption was observed in deep breathing than in steady breathing, and when expiration was suppressed for some time after inspiration, the rate increased remarkably to 97.4–99.7%. Prolonged retention of inhaled air containing mercury in the respiratory tract is believed to have caused the increased absorption.     

Biodegradation of Polycaprolactone Powders Proposed as Reference Test Materials for International Standard of Biodegradation Evaluation Method

Polycaprolactone (PCL) powders were prepared from PCL pellets using a rotation mechanical mixer. PCL powders were separated by sieves with 60 and 120 meshes into four classes; 0–125 μm, 125–250 μm, 0–250 μm and 250–500 μm. Biodegradation tests of PCL powders and cellulose powders in an aqueous solution at 25°C were performed using the coulometer according to ISO 14851. Biodegradation tests of PCL powders and cellulose powders in controlled compost at 58°C were performed by the Mitsui Chemical Analysis and Consulting Service, Inc. according to ISO 14855-1 and by using the Microbial Oxidative Degradation Analyzer (MODA) instrument according to ISO/DIS 14855-2. PCL powders were faster biodegraded than cellulose powders. The reproducibility of biodegradation of PCL powders is excellent. Differences in the biodegradation of PCL powders with different class were not observed by the ISO 14851 and ISO/DIS 14855-2. An enzymatic degradation test of PCL powders with different class was studied using an enzyme of Amano Lipase PS. PCL with smaller particle size was faster degraded by the enzyme. PCL powders with regulated sizes from 125 μm to 250 μm are proposed as a reference material for the biodegradation test.     

Simultaneous treatment of PVC and oyster-shell wastes by mechanochemical means

This work presents a new process for dechlorinating poly-vinyl chloride (PVC) by the use of oyster-shell waste. The process consists of milling of PVC waste with oyster-shell waste, followed by washing the milled sample with water. The milling of PVC and oyster-shell mixture results in size reduction and rupture in bonds, leading to mechanically induced reactions between the two to form CaCl2 and hydrocarbon with C=C bonds. Washing the milled mixtures with water at room temperature allows complete removal of chlorine from the milled sample. More than 95% of chlorine in PVC was removed when 2h grinding is conducted for the mixture. The present process could offer a potential route to the handling and disposal of oyster-shell and PVC wastes.     

Identification of methyl chloride-emitting plants and atmospheric measurements on a subtropical island

A survey of methyl chloride (CH3Cl)-emitting plants was performed at a subtropical island in Japan (Iriomote Island). Among the 187 species of tropical/subtropical plants investigated, 33 species from a variety of families were identified as CH3Cl-emitting plants. The strongest emitters were Osmunda banksiifolia, Cibotium balometz, Angiopteris palmiformis, Vitex rotundifolia, Vitex trifolia, and Excoecaria agalloch, each with CH3Cl emission rates exceeding 1microg (gdrywt)(-1)h(-1). The first three species are ferns, and the last three are halophilous plants. Based on our results, the character of CH3Cl emission is likely to be shared at the genus level but not always at the family level. The atmospheric CH3Cl distribution measured on Iriomote Island showed significant enhancement in forested sites (up to 2750 ppt) and a higher concentration on the downwind shore than on the upwind shore. As previously reported, our findings provide strong evidence for the high emission of CH3Cl from tropical/subtropical forests.